A basic example of such apparatus is disclosed in U.K. Pat. No. 769065. A more narrowly defined example of a sheet counting apparatus of this type is described in the U.K. Pat. No. 787624. The counting means in this disclosure is actuated upon rotation of the rotary assembly regardless as to whether or not the operative suction organ is bearing a sheet, and accordingly, means are provided to inhibit counting and rotation of said assembly if a predetermined degree of suction is not attain in the apparatus. In such an arrangement, the apparatus could fail to start if a suction organ was not correctly positioned against the face of the stack because the resulting air leakage would prevent the requisite suction being attained. Accordingly, the disclosure describes a method of ensuring that a suction organ is correctly positioned prior to operation of the apparatus and which is effected by reversing momentarily the rotary assembly until it is arrested by a stop means at an appropriate angular position.
The versatility of apparatus of the type described may be usefully extended by the provision of a "batching" facility, viz to enable the apparatus to deflect only a predetermined quantity of sheets, which is thereafter removed as a batch. However, while handling soft or worn sheets, we have found that difficulties may arise during reverse rotation of the apparatus because of the physical layout and geometry of the suction organs and the rotary assembly, and accordingly it is the object of the present invention to overcome the problem.